An Acoustic Technique for Evaluation of Thermal Insulation

A laboratory apparatus has been constructed that enables rapid measurement of the sound insertion loss of a sample of insulation as a function of frequency. An extensive series of measurements of the sound insertion losses associated with blown samples of fiberglass, rockwool, and cellulose has been completed; the results of these acoustic measurements are highly correlated with coverage (mass per unit area) and thermal resistance (R-value). An investigation is planned to extend the acoustic techniques used in the laboratory apparatus to in situ determination of the sound transmission loss through thermal insulation installed in attics. Two possible approaches to such field measurements are described.